Evidence suggesting that nitric oxide mediates iron-induced toxicity in cultured proximal tubule cells.
The potential role of nitric oxide (NO) in iron-induced toxicity was studied in proximal tubule cells in primary culture. NO production (NO2-/NO3-) was significantly increased in iron-treated compared with control cells (3.43 +/- 0.08 vs. 1.56 +/- 0.08 nmol/dish, P < 0.01). NO synthase (NOS) activity was also induced by iron treatment (16.2 +/- 2.0 vs. 0.4 +/- 0.2 nmol of [3H]citrulline/mg protein, P < 0.01). L-Arginine, a substrate for NOS, augmented iron-induced NO production and cell damage [lactate dehydrogenase (LDH) leakage], whereas aminoguanidine, an inhibitor of NOS, reduced iron-induced NO production and LDH leakage. Sodium nitroprusside, an exogenous NO donor, induced LDH leakage in a dose-dependent manner, but no effect on lipid peroxidation (malo-ndialdehyde bis[dimethyl acetal] (MDA) production) was observed. Superoxide dismutase and catalase decreased iron-induced MDA production but did not affect LDH leakage or NO production. Dimethylpyrroline N-oxide and desferal prevented MDA production, LDH leakage, and NO production. We concluded that NO is one of the mediators of iron-induced toxicity in proximal tubule cells. NO-induced toxicity is not dependent on lipid peroxidation. This may explain the variable effect of different antioxidants on cell damage and lipid peroxidation in iron-induced cytotoxicity.
Chen
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Department of Renal Medicine, University of Sydney, Westmead Hospital, New South Wales, Australia.
Zhang
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BH
Harris
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DC
D000818:Animals; D001120:Arginine / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006146:Guanidines / Q000494:pharmacology; D007501:Iron / Q000633:toxicity*; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D007770:L-Lactate Dehydrogenase; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D009573:Nitrites / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D004791:Enzyme Inhibitors; D006146:Guanidines; D009566:Nitrates; D009573:Nitrites; D009599:Nitroprusside; D009569:Nitric Oxide; D001120:Arginine; D007501:Iron; D007770:L-Lactate Dehydrogenase; D019001:Nitric Oxide Synthase; C004479:pimagedine